Heavy metals are major environmental pollutants, both in land and water. Heavy metal contamination is a threat because these metals are toxic and nonbiodegradable and therefore remain in the ecosystem and food chain. The toxicity of heavy metals may depend on the concentration of the heavy metal. For example, low concentrations of heavy metals such as zinc, iron and copper, are biologically essential. However, these metals may be toxic at higher concentrations. Heavy metals such as mercury and lead are not biologically essential and may cause various diseases in humans and animals, even at micro molar concentration levels.
Various techniques such as colorimetric analysis, impedance spectroscopy, Raman spectroscopy and titration have been used to detect heavy metals. However, known techniques may suffer from various drawbacks. For example, known heavy metal detection techniques may require complicated instrumentation, and may involve high manufacturing and operational costs.